Mechanism for preparing

ABSTRACT

A mechanism for preparing predetermined weft yarn lengths in a weaving machine having continuous unwinding of the yarn from a stationary yarn spool, comprising two buffer stores positioned substantially parallel to each other, each adapted to receive a weft yarn length in the form of a loop, a loop fixation device and a yarn supply means movable with its discharge opening between two end positions, each situated in front of an entrance mouth of a store, the arrangement being such that the yarn supply means supplies a yarn length to the one and the other buffer store and that the loop fixation device is operated each time when the supply means is transferred from the one to the other end station for fixing the loop length received in the one buffer store, wherein the buffer stores are positioned with their planes containing the loops opposite to each other and that the yarn supply means is movable in a plane perpendicular to the loop planes and containing the paths for the ingoing loop legs in both stores, the loop fixation device comprising at each end station a means that is operated when the supply means moves towards the other end station in order to keep the loop leg delivered previously by the supply means to the relative buffer store in its place, while between both stores a transfer means is reciprocally movable in the transverse direction for catching the yarn portion which has been drawn by the movement of the supply means from the one to the other end station, between said stations and transferring it to a point adjacent to the paths for the outgoing loop legs in both stores.

United States Patent 9] van Mullekom [54] MECHANISM FOR PREPARING PREDETERMINED WEFT YARN LENGTHS IN A WEAVING MACHINE Hubert Peter van Mullekom, Deurne, Netherlands [73] Assignee: N.V. Machinefabriek L. Te Strake,

Deurne, Netherlands [22] Filed: Dec. 22, 1971 [21] Appl. No.: 210,729

[75] Inventor:

[30] Foreign Application Priority Data [56] References Cited UNITED STATES PATENTS 3,587,664 6/1971 van Mullekom... .....l39/127 3,665,974 5/1972 Batten ..l39/127 3 ,675,687 7/1972 Vermeulen 139/127 Primary Examinerl1enry S. Jaudon Attorney-Marshall & Yeasting 1 May 22,1973

[57] ABSTRACT A mechanism for preparing predetermined weft yarn lengths in a weaving machine having continuous unwinding of the yarn from a stationary yarn spool, com prising two buffer stores positioned substantially parallel to each other, each adapted to receive a weft yarn length in the form of a loop, a loop fixation device and a yarn supply means movable with its discharge opening between two end positions, each situated in front of an entrance mouth of a store, the arrangement being such that the yarn supply means supplies a yarn length to the one and the other buffer store and that the loop fixation device is operated each time when the supply means is transferred from the one to the other end station for fixing the loop length received in the one buffer store, wherein the buffer stores are positioned with their planes containing the loops opposite to each other and that the yarn supply means is movable in a plane perpendicular to the loop planes and containing the paths for the ingoing loop legs in both stores, the loop fixation device comprising at each end station a means that is operated when the supply means moves towards the other end station in order to keep the loop leg delivered previously by the supply means to the relative buffer store in its place, while between both stores a transfer means is reciprocally movable in the transverse direction for catching the yarn portion which has been drawn by the movement of the supply means from the one to the other end station, between said stations and transferring it to a point adjacent to the paths for the outgoing loop legs in both stores.

10 Claims, 18 Drawing Figures PATENTED HAYZZIQYS 3 734, 1 4

SHEET 3 OF 7 PATENTED W2 21975 SHEET 5 0F 7 FIG. 11

PATENTEDHAYZZIQB SHEET 8 [IF 7 PATENTEUHAYZZHTS SHEET 7 BF 7 MECHANISM FOR PREPARING PREDETERMINED WEFT YARN LENGTI-IS IN A WEAVING MACHINE BACKGROUND OF THE INVENTION The invention relates to a mechanism for preparing predetermined weft yarn lengths in a weaving machine having continuous unwinding of the yarn from a stationary yarn spool, comprising two buffer stores substantially parallel to each other and each adapted for receiving a weft yarn length in loop shape, a loop fixation device and a yarn supply means movable with its discharge opening between two end stations, each situated in front of an entrance opening of a store, the arrangement being such that the yarn supply means supplies a yarn length to the one and to the other buffer store and that the loop fixation device each time becomes operative when the supply means is transferred from the one end station to the other for fixing the loop length received in the one buffer store.

A similar mechanism is known from the US. Pat. No. 3,443,603. Therein the buffer stores are positioned beside each other with the loops contained in the same plane, the end stations of the yarn supply means being situated at the oppositely directed longitudinal edges of the buffer stores and the yarn supply means being movable in the common plane of the yarn loops. The loop fixation device is essentially constituted by a yarn clamp provided between both buffer stores, midway the path of movement of the yarn supply means. Said known mechanism is adapted to prepare double weft yarn lengths which have to be woven hairpin shaped into the cloth, for which first one half and subsequently, after changing the weaving shed, the other half of the double weft yarn length is presented to the weft launching device. In connection herewith the yarn supply means is, moreover, pivotable between two positions in which the yarn supply means has its discharge opening directed towards the entrance mouths of the buffer stores and directed from said mouths respectively and at the same time is situated in the path of the said yarn clamp or in the path of a second yarn clamp combined with a yarn cutting means respectively. Finally a movable presenting needle cooperates with each buffer store which engages with the weft yarn length prepared in the associated buffer store and pres ents it to the launching device constituted by a blowing nozzle.

The invention aims at providing a simplified mechanism of this kind which is suitable for preparing single weft yarn lengths. The mechanismaccording to the invention is thereto characterized in that the buffer stores with their planes containing the loops are situated facing each other and in that the ayrn supply means is movable in a plane perpendicular to the loop planes and containing the paths for the ingoing loop legs in both stores, the loop fixation device comprising at each end station an element which, when the supply means moves towards the other end station, is operated to keep the loop leg delivered previously by the supply means to the relative buffer store in its place, while between both stores a transfer means is reciprocally movable in a transverse direction for catching the yarn portion that, when the supply means moves from the one to the other end station, is drawn between said stations and for transferring it to a point adjacent to the paths for the outgoing loops legs in both stores.

By using also for preparing single yarn lengths two buffer stores the advantage is obtained that during the launching of one measured yarn length from the one store, the next yarn length is already prepared in the form of a loop in the other store which last mentioned yarn length may be launched, after the yarn length having been launched already has been beaten up in the cloth, without more from the other store. The mechanism thereby contributes to a high weaving velocity and is essentially simpler than the above described known mechanism in that separate presenting needles are eliminated and in that the yarn supply means carries out a less complicated movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a simplified perspective view of the yarn preparing mechanism according to the invention in a first embodiment;

FIG. 2 is a plan view, of the lower buffer store of the mechanism according to FIG. l, the transfer lever being in its retracted position;

FIG. 3 shows a plan view similar to FIG. 2 but with the transfer lever in the outwardly moved position;

FIGS. 4-10 show a number of consecutive phases in the preparation of a predetermined weft yarn length in the one buffer store and the launching of a weft yarn length having been prepared previously from the other buffer store;

FIG. 11 shows a simplified schematic perspective view of the yarn preparing mechanism according to the invention in a second embodiment and FIGS. 1248 show a number of consecutive phases corresponding to the phases according to FIGS. 4-10, of the operation of said mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT The yarn preparing and presenting mechanism as shown in FIGS. 1-3 comprises two buffer stores 1 and 2 which in a known manner are embodied in the form of flattened tubes and which are provided in a horizontal positioniigidly with reference to the weaving machine frame. The buffer tubes 1 and 2 are adapted to receive alternately a length of the weft yarn, corresponding to the weaving width and drawn from the stationary yarn spool by means of a set of rollers '3, supplied by the pneumatic transport tube 5, which length is received in the shape of a loop, storing it temporarily and thereafter supplying it to the main blowing nozzle 7 provided on the mounting plate 6, which nozzle has to transport the yarn length by means of e.g. an air jet through the weaving shed not shown in the drawing.

In order to permit supplying the weft yarn in turn to the upper buffer tube 1 and to the lower buffer tube 2, the transport tube 5 is secured to a armed rocking lever 8 which is pivotable in a vertical plane around a shaft 9 journalled in a fixed part of the machine, between an upper position in which the discharge opening of the tube 5 is directed towards the entrance mouth of the upper buffer tube 1, and a lower position in which the discharge opening of the tube 5 is directed to the entrance mouth of the lower buffer tube 2. In both positions the discharge opening of the tube 5 is close to the longitudinal edge of the buffer tube 1 or 2 lying farthest from the viewer as seen in FIG. 1. The lever 9 is hingedly connected at its end remote from the buffer tubes 1 and 2 to a control rod 10 movable in the direction of the arrow 1, the movement of which is derived via a transmission mechanism not shown from the main shaft, likewise not shown, of the weaving machine.

To each of the buffer tubes 1 and 2, at the ends remote from the tube 5, not shown in the drawing, may be connected in a known manner an air suction device. A movable yarn clamp 11 or 12 respectively is associated with each of the buffer tubes 1 and 2, formed by a clamp rod extending transversely to the buffer tube, which rod may clamp a weft yarn received in the buffer tube against the underlying or the overlying edge portion respectively adjacent to the entrance mouth of said buffer tube. The clamp rods 11 and 12 are each secured to one end of a connected rod 13 or 14 respectively which with its other end is connected pivotally in a vertical plane to the sector shaped widened arm 15 of the lever 6. The pivot points 16 and 17 are situated one above the other, as well as the connecting rods 13, 14 and the clamp rods 11 and 12.

According to FIG. 1 the lever 8 is in its lower position i.e. the position in which the discharge opening of the transport tube 5 is directed to the entrance mouth of the lower buffer tube 2. The lower clamp rod 12 is free from the edge portion of the lower buffer tube 2, situated over said rod, while the connecting rod 14 engages the underside of a lower abutment 19 on the lever arm 15. The connecting rod 14 of the lower clamp rod 12 is connected through a tension spring 20 with the connecting rod 13 of the upper clamp rod 11, which last mentioned rod thereby is resiliently drawn against the underlying edge portion of the upper buffer tube 1. The connecting rod 13 is then free from an upper abutment 18 on the lever arm 15. In the situation according to FIG. 1 the lower clamp rod 12 therefore is open while the upper clamp rod 11 is closed. FIG. 1 shows how in this position a weft yarn length a, which forms the ingoing leg of the yarn loop to be temporarily stored in the upper storing tube 1, is clamped to the mouth of the upper buffer tube betweeen the clamp rod 11 and the edge portion of the buffer tube situated thereunder.

A transfer lever 21 is mounted to pivot around a fixed point 22 on a vertical axis and extends in the space between the upper and the lower buffer tubes 1 and 2, said space having in reality, at least at the entrance mouths of the buffer tubes, less hieght than is shown in the drawing. The lever 21 has a hook end 23 projecting just before the mouths of the buffer tubes 1 and 2, which serves to catch when pivoted in the direction of the arrow the yarn portion extending in FIG. 1 from the underlying discharge opening of the transport tube 5 upwardly to the clamp rod 11 and to transfer said portion to a point closer to the longitudinal edges of the buffer tubes 1 and 2 in the foreground, namely particularly to the hook 24 of a take-over lever 27, pivotally mounted on a vertical shaft 25 journalled in a block 26 on the mounting plate 6. The lever 27 is maintained in the operative position as shown in FIG. 1 by a spring 28 tensioned between an anchoring eyelet 29 projecting upwardly from the mounting plate 6 and the free end of a projecting arm 27a of the lever 27. As is visible in FIG. 1 the hook end 23 of the transfer lever 21 is slotted in a horizontal central longitudinal plane of the lever, through which slot (230) the take-over lever 27 may project when the transfer lever 21 is pivoted in the direction of the arrow.

The cooperation between the levers 21 and 27 is now described more in detail with reference to FIGS. 2 and 3. Said figures show that the lever 21 is provided with an arm 30 extending in the direction of the arrow 11, a bell-crank two-armed lever 31 being mounted on the free end of said arm to pivot around a vertical shaft 32. The free end of the arm 31a of the lever 31 is connected by a tension spring to the lever 21, the twoarmed lever 31 being pressed under the influence of said tension spring with a roller 34 carried by the free end of tis arm 31b against an upstanding abutment edge 35 of the arm 30. The lever 27 is coupled rigidly for totation to an abutment lever 36 mounted at a somewhat lower level to the shaft 25, said abutment lever 36 extending under the lever 21 and the bell-crank lever 31 in a transverse direction through the space between the upper and the lower buffer tubes 1 and 2. Said abutment lever has an upstanding abutment edge 37 which cooperates with the roller 34 so that when the lever 21 is pivoted in the direction of the arrow 11 (FIG. 2) the roller 34 contacts the abutment edge 37 whereby the abutment lever 36 is pivoted in the direction of the arrow III and takes the take-over lever 27 with it. FIG. 3 shows the mechanism according to FIG. 2 in the position in which the take-over lever 27 is in its most retracted position but in which the lever 21 has already been rotated so far that the roller 34 has just been released the abutment edge 37 of the abutment lever 36, so that said lever 36 is about to return to the operative position according to FIG. 2 together with the takeover lever 27 under the influence of the action of the spring 28. It will be clear that when the lever 21 there after returns to its starting position according to FIGS. 1 and 2 the yarn length, which is still hooked around the hook end 23 of said lever, is caught by the hook 24 of the lever 27, which in the mean time has returned to its operative position, at the moment in which the hook end 23 of the lever 21 moves over the hook portion of the lever 27 and is released thereby.

The transfer lever 21 is controlled by a control rod 38 engaging a projecting arm 21 of said lever and movable in the direction of the arrow, the movement of said rod being derived through a mechanism not shown from the main shaft of the weaving machine.

Apart from the parts described already, FIG. 1 shows further a yarn guiding eyelet 39, a yarn clamp 40 and a cutting device 41. The yarn guiding eyelet 39 serves for receiving the second leg or outgoing leg b of the yarn loop received in one of the buffer tubes and for guiding it towards the main blowing nozzle 7. The movable portion 40a of the yarn clamp 40 provided downstream from the main blowing nozzle 7 is operated in the opening or closing direction respectively by a control rod movable in the direction of the arrow V, the movement of which is again derived through a transmission mechanism not shown from the main shaft of the weaving machine. The yarn clamp 40 closes immediately after a weft yarn has been introduced into the weaving shed by the main blowing nozzle and remains closed until the reed of the weaving machine has beaten up the yarn weft into the cloth.

The process of the yarn preparation is now explained more in detail with reference to FIG. 1 and FIGS. 4-10. FIG. 1 shows the yarn preparing mechanism at the moment in which a yarn loop (a b) with a total length corresponding to the weaving width, has just been received in the upper buffer tube, ready to be introduced into the weaving shed to form the next weft. The upper clamp rod 11 has just been closed, the transfer lever 21 is about to carry out a pivotal movement in the direction of the arrow II and the blowing nozzle 7 is about to introduce, at the same time when the yarn clamp 40 is opened, the yarn length provided in the buffer tube 1 into the weaving shed.

FIG. 4 shows the situation a short moment after that according to FIG. 1, which moment corresponds to some degrees of revolution of the main shaft of the weaving machine. The blowing nozzle 7 has just started, with the yarn clamp 40 opened, the launching of the prepared yarn length through the weaving shed, while the transfer lever 21 has caught the yarn portion extending in FIG. 1 between the closed clamp rod 11 and the tube 5 and has moved it within the operating range of the take-over lever 27. The yarn portion indicated at c in FIG. 4 constitutes the beginning of the yarn loop which is about to be blown by the transport tube 5 positioned before the mouth of the lower buffer tube 2 and supported by the suction generated in said buffer tube.

FIG. 5 relates to a moment midway of the launching of the yarn loop length (a b). It appears from said figure how during the launching of the yarn loop (a b) a new yarn loop (a b) is forming from the yarn portion according to FIG. 4.

FIG. 6 relates to the moment in which the launching of the yarn loop (a b) has been completed. The yarn clamp 40 has just closed and the reed, not shown, is about to beat up the just launched weft yarn into the cloth. The forming of the yarn loop in the lower buffer tube continues, but has to be finished before the yarn clamp 40 reopens. The forming of the new loop (a' b) in the lower tube is completed at the moment in whch the lower clamp rod 12 closes. At the same time the upper clamp rod 11 opens whereby the yarn portions indicated at x is released by the clamp rod 11 and may be drawn taut under the influence of the suction in the lower buffer tube 2. The moment at which said last mentioned action has beeon completed is shown by FIG. 7. The total length of the new loop (a' b) is fixed by the closing of the lower clamp rod 12, the yarn clamp 40 is about to open after the completion of the previous beating up by the reed the cutting device is cutting the yarn inserted and just beaten up into the cloth near the yarn clamp 40 and the blowing nozzle 7 is about to launch the thus fixed yarn loop length (a' b). In the meantime the transport tube has arrived, with the closing of the lower clamp rod 12 and the opening of the upper clamp rod 11, in front of the mouth of the upper and now emptied buffer space 1, while the transfer lever 21 is about to bring the yarn portion extending between the discharge opening of the tube 5 and the lower clamp rod 12 into the working range of the take-over lever 27. FIG. 8 shows the situation at a moment shortly after that according to FIG. 7, corresponding to soame degrees of revolution of the main shaft of the weaving machine. The blowing nozzle 7 has jsut started, after opening of the yarn clamp 40, the launching of the prepared yarn length (a' b) through the weaving shed, while the transfer lever 21 has caught the yarn portion extending in FIG. 7 between the closed clamp rod 12 and the tube 5 and brought this portion within the working range of the take-over lever 27. the yarn portions indicated at c in FIG. 8 forms the beginning of a new yarn loop which is about to be blown by the transport tube 5, present in front of the mouth of the upper buffer tube 1, and supported by the suction action in said buffer tube.

FIG. 9 relates to a moment midlway of the launching of the yarn loop length (a' b). It appears from said figure how during the launching of the yarn loop (a b) a new yarn loop (11" b") is forming from the yarn portion 0 in FIG. 8.

FIG. 10 relates to the moment in which the launching of the yarn loop (a' b) has been completed. The yarn clamp 40 has just closed and again the reed is about to beat up the just launched weft yarn into the cloth. The forming of the yarn loop in the upper buffer tube 1 continues up to a moment shortly before the yarn clamp 40 reopens. The forming of the new loop (a" b) in the upper buffer is completed at the moment in which the upper clamp rod 11 closes. At the same time the lower clamp rod 12 opens, whereby the yarn portion indicated at x is released by the clamp rod 12 and may be drawn taut under the influence of the suction in the upper bufier tube 1. At the moment in which said last mentioned action has been completed, the starting position according to FIG. 1 is reached again and the above described process is repeated.

The embodiment according to FIG. 11 differs from that according to FIGS. 1-3 with reference to the embodiment of the transfer lever and to the manner of fixing the consecutive yarn lengths to be received in the buffer stores. Instead of the clamp rods 11 and 12 of the embodiment according to FIGS. 1-3, in the embodimet according to FIG. 11 the guiding pins indicated at 42 and 43 are applied, which are formed by the end portions, bent through of the connecting rods 13 and 14 respectively. In FIG. 11 the lever 8 is, as in FIG. 1, in its lower position. The upper guiding pin 42 is drawn under the influence of the spring 20 against the underlying edge portion of the buffer tube 1 and thereby keeps the weft yarn length a at the longitudinal side, situated in the background, of the buffer tube 1. The lower guiding pin 43 is completely free from the lower buffer tube 2.

The transfer lever 21 is at its free end provided with a yarn clamp 44 which has been substituted for the hooked end 23 in the embodiment according to FIGS. 1-3. The yarn clamp 44 is secured to the one end of a rod 45 which is guided slidably in the longitudinal direction in the lever 21 and supports at its end remote from the clamp 44 a circle segment 46, the centre of curvature of which is situated in the pivot point 22 of the lever 21. A spring 47 is provided around the portion of the rod 45 which projects at the end remote from the clamp 44 beyond the lever 21, which spring tends to close the clamp 44. A control cam 49, provided on a shaft 48, acts on the segment 46 and intermittenlty opens the clamp 44 against the action of the spring 47. The clamp 44 is open in the starting position of the transfer lever 21, indicated in FIG. 11, and closes after the yarn length situated between the tube 5 and the upper guiding pin 42 has been caught. Thereafter the clamp 44 remains after the transfer lever has arrived in its outer position closed during some time, namely until shortly before a yarn loop has been completed in the lower buffer tube 2 (vide the phases according to FIGS. 12 and 13 which are comparable with the phases according to FIGS. 4 and 5). Different from the mechanism according to FIGS. 1-3 the transfer lever 21 does not, after reaching its outer position, immediately return to its starting position, but remains in its outer position during some time, namely until about the time in which the clamp 44 is closed. This is in connection with the circumstance, that in the mechanism according to FIG. 11 the take-over lever 27 of the mechanism according to FIGS. l-3 has been eliminated and that the function of said take-over lever is now fulfilled by the lever 21.

The lever 21 does not return to its starting psoition after opening of the clamp 44 until the phase according to FIG. 14, comparable to the phase 6, is reached whereafter it catches the yarn portion which is drawn by the transport tube 5, pivoting to its outer position between the lower and the upper buffer tube (vide FIG. 15) and therewith fixes the length of the loop in the lower buffer tube 2. The phases in the yarn preparation following thereon, according to FIGS. 16-18, now speak for themselves and therefore need no further explanation.

I claim:

1. A mechanism for preparing predetermined weft yarn lengths in a weaving machine having continuous unwinding of the yarn from a stationary yarn spool, comprising two buffer stores positioned substantially parallel to each other, each adapted to receive a weft yarn length in the form of a loop, a loop fixation device and a yarn supply means movable with its discharge opening between two end stations, each situated in front of an entrance mouth of a buffer store, the arrangement being such that the yarn supply means supplies a yarn length to the one and the other buffer store and that the loop fixation device is operated each time when the supply means is transferred from the one to the other end station for fixing the loop length received in the one buffer store, characterized in that the buffer stores are positioned with their planes containing the loops opposite to each other and that the yarn supply means is movable in a plane perpendicular to the loop planes and containing the paths for the ingoing loop legs in both stores, the loop fixation device comprising at each end station a means that is operated when the supply means moves towards the other end station in order to keep the loop leg delivered previously by the supply means to the relative buffer store in its place, while between both stores a transfer means is reciprocally movable in the transverse direction for catching the yarn portion which has been drawn by the movement of the supply means from the one to the other end station, between said stations and transferring it to a point adjacent to the paths for the outgoing loop legs in both stores.

2. A mechanism according to claim 1, characterized in that the means for keeping the ingoing loop legs in their places each comprise a yarn clamp and that the transfer means has a hook shaped catching portion which may slidably engage the yarn portion to be caught.

3. A mechanism according to claim 2, characterized in that the transfer means cooperates with a hook shaped means provided adjacent to the outgoing loop legs, for taking over the relative yarn portion from the transfer means.

4. A mechanicm according to claim 3, characterized in that the transfer means and the take-over means cooperate such that during the upstroke movement of the transfer means the take-over means retracts from the path of the hook shaped portion of the transfer means and therefore from the yarn portion taken along therein and enters before the downstroke or retracting movement of the transfer means into said path in order to take over the relative yarn portion from the transfer means.

5. A mechanism according to claim 4, characterized in that the transfer means is constituted by a lever mounted pivotally between the stores in a plane parallel to the loop planes, the take-over means comprising a pivotable hook which is kept by a spring in its operative take-over position and may pass through a slot in the hook portion of the transfer lever, the transfer lever having a projecting arm with a resilient abutment means which in the upstroke movement of the transfer lever cooperates with an abutment on a part of the take-over hook, but in the retracting movement remains free thereform, the arrangement being such that the take-over hook in the upstroke movement of the transfer lever is retracted from its operative take-over psoition, but springs back into that position after the passing of the transfer lever and remains therein during the return movement of the transfer lever.

6. A mechanism according to claims 2, characterized in that both yarn clamps each comprise a transversely positioned clamping rod which is connected by a connecting rod to a rocking lever carrying the yarn supply means and moving between both stations, both clamping rods cooperating with the edge portions of the entrance mouth of the buffer stores facing each other and serving as fixed clamping surfaces.

7. A mechanism according to claim 6, characterized in that the connecting rods are pivotally connected at their ends remote from the clamping rods to the rocking lever and in that said connecting rods are drawn towards each other by a connecting spring, each connecting rod cooperating with an abutment on the rocking lever, the arrangement being such that each time the connecting rod of the inoperative clamping rod rests against its abutment and resiliently draws, via the connecting spring, the other clamping rod, the connection rod of which remains free from the associated abutment, to its operative clamping position.

8. A mechanism according to claim 1, characterized in that the means for keeping the ingoing loop legs in their places each comprise a guiding pin movable between an operative position within the mouth and an operative position outside the mouth of the relative buffer store, the transfer means comprising a yarn clamp which may open and close in both end positions of the transfer means.

9. A mechanism according to claim 8, characterized in that the guiding pins are each connected by a connecting rod to a rocker lever carrying the yarn supply means and movable between both end stations, and rest in their operative position on the edge portions of the mouths of the buffer stores facing each other.

10. A mechanism according to claim 9, characterized in that the connecting rods are connected pivotally at their ends remote from the guiding pins to the rocking lever, and in that said connecting rods are drawn by a connecting spring towards each other, each connecting rod cooperating with an abutment on the rocking lever, the arrangement being such that each time the connecting rod of the inoperative guiding pin rests against its abutment and resiliently draws, via a connecting spring, the other guiding pin, the connecting rod of which remains free from the associated abutment, to its operative clamping position. 

1. A mechanism for preparing predetermined weft yarn lengths in a weaving machine having continuous unwinding of the yarn from a stationary yarn spool, comprising two buffer stores positioned substantially parallel to each other, each adapted to receive a weft yarn length in the form of a loop, a loop fixation device and a yarn supply means movable with its discharge opening between two end stations, each situated in front of an entrance mouth of a buffer store, the arrangement being such that the yarn supply means supplies a yarn length to the one and the other buffer store and that the loop fixation device is operated each time when the supply means is transferred from the one to the other end station for fixing the loop length received in the one buffer store, characterized in that the buffer stores are positioned with their planes containing the loops opposite to each other and that the yarn supply means is movable in a plane perpendicular to the loop planes and containing the paths for the ingoing loop legs in both stores, the loop fixation device comprising at each end station a means that is operated when the supply means moves towards the other end station in order to keep the loop leg delivered previously by the supply means to the relative buffer store in its place, while between both stores a transfer means is reciprocally movable in the transverse direction for catching the yarn portion which has been drawn by the movement of the supply means from the one to the other end station, between said stations and transferring it to a point adjacent to the paths for the outgoing loop legs in both stores.
 2. A mechanism according to claim 1, characterized in that the means for keeping the ingoing loop legs in their places each comprise a yarn clamp and that the transfer means has a hook shaped catching portion which may slidably engage the yarn portion to be caught.
 3. A mechanism according to claim 2, characterized in that the transfer means cooperates with a hook shaped means provided adjacent to the outgoing loop legs, for taking over the relative yarn portion from the transfer means.
 4. A mechanicm according to claim 3, characterized in that the transfer means and the take-over means cooperate such that during the upstroke movement of the transfer means the take-over means retracts from the path of the hook shaped portion of the transfer means and therefore from the yarn portion taken along therein and enters before the downstroke or retracting movement of the transfer means into said path in order to take over the relative yarn portion from the transfer means.
 5. A mechanism according to claim 4, characterized in that the transfer means is constituted by a lever mounted pivotally between the stores in a plane parallel to the loop planes, the take-over means comprising a pivotable hook which is kept by a spring in its operative take-over position and may pass through a slot in the hook portion of the transfer lever, the transfer lever having a projecting arm with a resilient abutment means which in the upstroke movement of the transfer lever cooperates with an abutment on a part of the take-over hook, but in the retracting movement remains free thereform, the arrangement being such that the take-over hook in the upstroke movement of the transfer lever is retracted from its operative take-over psoition, but springs back into that position after the passing of the transfer lever and remains therein during the return movement of the transfer lever.
 6. A mechanism according to claims 2, characterized in that both yarn clamps each comprise a transversely positioned clamping rod which is connected by a connecting rod to a rocking lever carrying the yarn supply means and moving between both stations, both clamping rods cooperating with the edge portionS of the entrance mouth of the buffer stores facing each other and serving as fixed clamping surfaces.
 7. A mechanism according to claim 6, characterized in that the connecting rods are pivotally connected at their ends remote from the clamping rods to the rocking lever and in that said connecting rods are drawn towards each other by a connecting spring, each connecting rod cooperating with an abutment on the rocking lever, the arrangement being such that each time the connecting rod of the inoperative clamping rod rests against its abutment and resiliently draws, via the connecting spring, the other clamping rod, the connection rod of which remains free from the associated abutment, to its operative clamping position.
 8. A mechanism according to claim 1, characterized in that the means for keeping the ingoing loop legs in their places each comprise a guiding pin movable between an operative position within the mouth and an operative position outside the mouth of the relative buffer store, the transfer means comprising a yarn clamp which may open and close in both end positions of the transfer means.
 9. A mechanism according to claim 8, characterized in that the guiding pins are each connected by a connecting rod to a rocker lever carrying the yarn supply means and movable between both end stations, and rest in their operative position on the edge portions of the mouths of the buffer stores facing each other.
 10. A mechanism according to claim 9, characterized in that the connecting rods are connected pivotally at their ends remote from the guiding pins to the rocking lever, and in that said connecting rods are drawn by a connecting spring towards each other, each connecting rod cooperating with an abutment on the rocking lever, the arrangement being such that each time the connecting rod of the inoperative guiding pin rests against its abutment and resiliently draws, via a connecting spring, the other guiding pin, the connecting rod of which remains free from the associated abutment, to its operative clamping position. 